Reinforcing threads and composites resistant to corrosive media

ABSTRACT

The present invention relates to reinforcement yarns coated with a sizing composition comprising at least one silane satisfying the formula: 
 
Si(R 1 ) (R 2 ) (R 3 ) (R 4 ) 
in which: 
         R 1 , R 2  and R 3  are chosen from the following atoms or groups:    —H (except in the case of R 3 ), —Cl, —O—R 5 , —O—R 6 —O—R 5 , —O—(C═O)—R 5 , —O—R 6 —(C═O)—R 5 , R 5  and R 6  being chosen from hydrocarbon radicals whose main chain has from 1 to 4 carbon atoms;    R 4 ═—R 7 —NHR 8  R 7  being chosen from branched hydrocarbon radicals whose main chain has from 2 to 6 carbon atoms, R 8  being chosen from the following groups:    —H, —R 9 —NH 2 , —R 10 —NH—R 9 —NH 2 , R 9  being chosen from hydrocarbon radicals containing 1 to 12 carbon atoms or from carbonyls, and R 10  being chosen from hydrocarbon radicals whose main chain has from 1 to 6 carbon atoms. The glass yarns according to the invention are particularly suitable for reinforcing organic materials, the yarns and composites obtained resisting in a corrosive medium.

The present invention relates to yarns (or fibers) capable ofreinforcing organic and/or inorganic materials and to the reinforcedproducts (or composites) obtained, these reinforcement yarns and thesecomposites being able to be used in a corrosive medium (wet medium, acidmedium or basic medium).

The present invention relates in particular to glass reinforcement yarnsthat can be obtained by mechanically drawing, at high speed (up toseveral tens of meters per second), molten glass strands flowing out oforifices made in the base of a bushing (or die). These strands are drawninto the form of filaments, which are coated, before they are assembledinto yarns, with a composition called a sizing composition intended inparticular to protect the yarns from abrasion and to promote adhesionbetween the glass and the material to be reinforced.

The most common glass reinforcement yarns are based on E-glass, thecomposition of this glass being derived from the 1 170° C eutectic ofthe SiO₂—Al₂O₃—CaO ternary diagram (cf. patents U.S. Pat. No. 2,334,961and U.S. Pat. No. 2,571,074 which present the archetype of theseglasses). In most cases, these E-glass yarns, coated with conventionalsizes, are suitable for reinforcing organic materials and make itpossible to produce composites with good mechanical properties. However,when these yarns or the composites produced from these yarns are used incorrosive—wet, acid or basic—media over a long time and/or under highstresses (for example yarns used to reinforce cement or composites inprolonged contact with an acid), an appreciable reduction in themechanical properties of the composites formed is observed over thecourse of time.

There are also AR (alkali-resistant) glass yarns which, when also coatedwith conventional sizing compositions, make it possible to obtaincomposites more able to attain good mechanical properties over time inacid medium and above all in basic medium (whether this medium is formedby the material to be reinforced or is that in which the composites areused). The composition of these glasses generally contains a highproportion of zirconium oxide and is, for example, of the Na₂O—ZrO₂—SiO₂type. A conventional composition of these glasses is given for examplein patent GB 1 290 528. However, these yarns remain sensitive to wetmedium, such yarns furthermore adhering less strongly to organicmaterials than E-glass yarns and thus limiting their use to the directreinforcement (without an intermediate organic material) of inorganicmaterials such as cement.

The objective of the present invention was to develop composites moreresistant in a corrosion medium, preferably in various corrosive mediaand in particular in a wet medium (the most common corrosive medium,moisture already being present in the ambient air) and/or to broaden therange of products that can be used in such media, in particular infields for which the abovementioned glass yarns are not the mostsuitable or for which the products currently used are not entirelysatisfactory, for example in the field of manufacturing hollow bodies byfilament winding, in particular for storing or transporting variouschemicals, or in the field of pultrusion (for example with a view toreplacing conventional concrete rebars with composite products).

This objective is achieved by the present invention by providingreinforcement yarns allowing composites to be obtained with mechanicalproperties that are better in at least one corrosive medium(advantageously a wet medium) than each of the aforementioned respectiveexisting yarns, the yarns according to the invention also allowing themanufacture of high-performance composites suitable for theabovementioned applications.

The reinforcement yarns according to the invention (preferably glassyarns) are coated with a sizing composition comprising (or one of theinitial constituents of which is) at least one silane satisfying thefollowing formula:Si(R¹)(R²)(R³)(R⁴)in which:

-   -   R¹ and R² are chosen from the following atoms or groups:    -   —H, —Cl, —O—R⁵, —O—R⁶—O—R⁵, —O—(C═O)—R⁵, —O—R⁶—(C═O)—R⁵;    -   R³ is chosen from the following atoms or groups: —Cl, —O—R⁵,        —O—R⁶—O—R⁵, —O—(C═O)—R⁵, —O—R⁶—(C═O)—R⁵;    -   R⁵ and R⁶ being chosen from hydrocarbon radicals whose main        chain has from 1 to 4 carbon atoms;    -   R⁴═—R⁷—NHR⁸;    -   R⁷ being chosen from branched hydrocarbon radicals whose main        chain has from 2 to 6 carbon atoms;    -   R⁸ being chosen from the following groups:    -   —H, —R⁹—NH₂, —R¹⁰—NH—R⁹—NH₂;    -   R⁹ being chosen from hydrocarbon radicals containing from 1 to        12 carbon atoms or from carbonyls; and    -   R¹⁰ being chosen from hydrocarbon radicals whose main chain has        from 1 to 6 carbon atoms.

The term “hydrocarbon radical” is understood to be advantageously aradical (or group) formed solely from carbon and hydrocarbon atoms, saidradical being branched or unbranched and being derived (removal, in thecase of a monovalent radical, of one hydrogen atom of a hydrocarbon or,in the case of a divalent radical, removal of two hydrogen atoms from ahydrocarbon) from a saturated hydrocarbon or hydrocarbon possibly havingone or more multiple bonds (double bond, triple bond), and being acyclicor possibly cyclic or even, in the case of R⁹, able to include a benzenering. In the case of a branched hydrocarbon group, the secondary chainor chains each advantageously have from 1 to 4 carbon atoms.

The R¹, R² and R³ groups may be identical or different. Likewise, R⁵ andR⁶ may be derived from identical or different hydrocarbons. Preferably,R¹ is chosen from the following atoms or groups: —H, —OR⁵ (alkoxygroup), —O—R⁶—O—R⁵, —O—(C═O)—R⁵ (acetoxy group) and R² and R³ are chosenfrom the following groups: —OR⁵, —O—R⁶—O—R⁵, —O—(C═O)—R⁵. Alsopreferably, R⁵ and R⁶ are chosen respectively from alkyl radicals andalkylidene radicals containing from 1 to 3 carbon atoms. Moreparticularly preferably, R¹, R² and R³ are chosen from alkoxy groups (inparticular from methoxy, ethoxy and propoxy groups).

The radical R⁷ is branched (or substituted) with one or more side chains(or groups or radicals) formed solely from carbon and hydrogen atoms,each of these side chains comprising from 1 to 4 carbon atoms, which maybe linear (for example in the form of a linear alkyl such as a methyl orethyl) or in the form of a branched chain (for example an isopropyl) andmay possibly be able to have multiple bonds (for example an alkylenyl).Preferably, the R⁷ radical is derived from a saturated hydrocarbon andis acyclic. Also advantageously, the R⁷ radical is preferably branchedby alkyl groups, in particular branched by at least two side chains,which may or may not be carried by the same carbon of the main chain(and particularly preferably by one or more of the carbons in themiddle, or the more at the center, of the main chain comprising at leastthree carbon atoms), the side chains being chosen from alkyls containingfrom 1 to 3 carbon atoms.

The R⁹ radical is preferably chosen from the following (divalent)radicals: a branched or unbranched, cyclic or acyclic, alkylideneradical, the main chain of which has from 1 to 6 carbon atoms, a phenylradical, an alkylphenyl radical combining the above two radicals typesor possibly an alkenylphenyl, and a carbonyl radical —(C═O)—. The R¹⁰radical is preferably an alkylidene radical.

Advantageously, the R⁸ radical is chosen from the following atoms orgroups —H, —R⁹—NH₂.

One particularly advantageous silane satisfying the definition of theinvention is that in which R¹═R²═R³═—CH₃O and in whichR⁴═—CH₂—CH₂—C(CH₃)₂—CH₂—NH₂ (i.e. R⁷═—CH₂—CH₂—C(CH₃)₂—CH₂— and R⁸═—H),i.e. amino-4-dimethyl-3,3-butyltrimethoxysilane or else possibly that inwhich R¹═R²═R³═—CH₃O and R⁴═—CH₂—C(CH₃)₂—CH₂—NH₂ (i.e.R⁷═—CH₂—C(CH₃)₂—CH₂— and R⁸═—H), i.e.amino-3-dimethyl-2,2-propyltrimethoxysilane.

The present invention also relates to the sizing composition used tocoat the yarns, this composition comprising at least one silanesatisfying the formula defined above.

The use of the composition defined according to the invention to coatyarns intended to be used as reinforcements in a corrosive medium hasresulted in an improvement, either initially or over time (smallerreduction in a property for a given time), in at least one given (wet,acid or basic) medium, in particular in at least a wet medium, of atleast one mechanical property of the composites formed from the yarnsthus coated compared with the composites formed from yarns of the samebase composition (for example the same glass composition) but coatedwith conventional sizing compositions. Furthermore, it has been observedthat the yarns according to the invention are capable of reinforcingboth organic materials and inorganic materials and that this is sowhatever the base composition of these yarns (particularly when theseyarns are AR glass yarns). These yarns are consequently suitable forbeing used in new fields of application and, if appropriate, in a broadrange of corrosive media (in particular at least a wet medium), theobserved improvement depending on the type of glass yarn coated, on thematerial reinforced and on the corrosive medium in question.

As indicated above, the yarns according to the invention are preferablyglass yarns, these yarns generally being prepared using processes knownper se. In general, the glass yarns according to the invention aremanufactured in the following manner: molten glass strands aremechanically drawn (at speeds of several tens of meters per second) intothe form of one or more sheets of continuous filaments from the orificesof one or more bushings (or dies), and then the filaments (generallyhaving a diameter between 5 and 24 μm) are coated with the sizingcomposition according to the invention before being assembled into oneor more yarns. These yarns may then be wound onto rotating supports,distributed on moving conveyors, in order to form mats or veils, or elsechopped, either after formation by the unit used to draw them, or in asubsequent operation. Where appropriate, the yarns may, before or afterbeing collected, be subjected to a heat treatment so as, for example, todry them and/or to cure them.

Preferably, the yarns according to the invention are collected in theform of windings (for example rovings or cakes). In particular when theyarns according to the invention are AR glass yarns, these windings mayadvantageously be used for the manufacture of hollow bodies (such aspipes and tanks) by filament winding (deposition of a reinforcement, forexample a sheet of rovings, impregnated with an organic material on amandrel rotated about its axis), it being possible for these hollowbodies to transport or store chemicals, or these packages may be usedfor the manufacture of composite profiles by pultrusion (passage of areinforcement impregnated with an organic material through a heateddie), these profiles being used, for example, in the manufacture ofreinforcements for reinforced concrete. The present invention has thusallowed novel products to be developed, such as composite reinforcementsor bars based on AR glass yarns according to the invention that canadvantageously replace conventional concrete rebars.

The glass yarns according to the invention may be obtained from any typeof glass normally used for producing glass reinforcement yarns. Theyarns according to the invention may especially be E-glass yarns, “R”(mechanically strong)-type glass yarns or “S”-type glass yarns based onsilica, alumina, magnesium and optionally lime, alkali-resistant glassyarns, yarns based on compositions containing no boron, etc.

Preferably, the glass yarns according to the invention are yarns of“alkali-resistant” (AR) glass, this glass generally containing zirconiumoxide ZrO₂. These yarns may be chosen from any existing alkali-resistantglass yarns (such as those described in patents GB 1 290 528, U.S. Pat.No. 4,345,037, U.S. Pat. No. 4,036,654, U.S. Pat. No. 4,014,705, U.S.Pat. No. 3,859,106, etc.) and preferably contain at least 5 mol % ZrO₂.According to one embodiment of the invention, the constituent glass ofthe yarns comprises SiO₂, ZrO₂ and at least one alkali metal oxide,preferably Na₂O, as principal constituents.

One alkali-resistant glass composition particularly used for producingthe glass yarns according to the invention is the composition describedin patent GB 1 290 528, composed mainly of the following components inthe proportions expressed as molar percentages: 62-75% SiO₂; 7-11% ZrO₂;13-23% R₂O; 1-10% R′O; 0-4% Al₂O₃; 0-6% B₂O₃; 0-5% Fe₂O₃; 0-2% CaF₂;0-4% TiO₂; R₂O representing one or more alkali metal oxides, preferablyNa₂O, and optionally (up to 2%) Li₂O, and R′O being one or morecomponents chosen from alkaline-earth oxides, ZnO and MnO.

Particularly advantageously, the alkali-resistant glass yarns as definedaccording to the invention meet the objectives of the invention—inparticular they make it possible to obtain composites having goodmechanical properties in a corrosive medium, whether in a wet, acid orbasic medium (broad range of possible applications, particularly use inapplications in which the corrosive medium is liable to change), theimprovement being observed especially in a wet medium, over time andpossibly initially. In addition, the AR glass yarns according to theinvention combine particularly satisfactorily with organic materials(and not just with inorganic materials), making it possible to obtainnovel composite products based on AR glass and organic material(s), suchas those mentioned above, these novel products also being covered by thepresent invention.

The sizing composition coating the yarns according to the invention maybe an aqueous or anhydrous composition or it may contain, for example,less than 5% by weight of compounds acting solely as a solvent. In mostcases, the composition according to the invention is an aqueouscomposition containing between 85 and 98% water by weight and being inthe form of an aqueous dispersion (emulsion, suspension, emulsionmixture and/or suspension mixture) or of a solution.

If the sizing composition according to the invention is in the form ofan aqueous dispersion or solution, the solids content of the compositionis generally between 2 and 15% by weight of the composition.

According to the definition of the invention, the composition comprisesa particular silane satisfying the formula given above, this silaneacting not only as a coupling agent, as usually observed with silanes,but also acting, it would seem, as a protective agent. For this purposeand so as to distinguish it from the usual silanes acting only ascoupling agents, the silane satisfying the abovementioned formula ishereafter denoted by the term “protection agent”. It seems in particular(without however being limited to this supposition) that said silane hasthe double advantage of protecting the surface of the reinforcementyarns, particularly from moisture, without correspondingly impairing, inparticular, impregnation with organic materials.

It is possible to use one or more protection agents according to theinvention. Preferably, the composition comprises a single protectionagent according to the invention.

The content of protection agent(s) according to the invention within thesizing composition is generally between 1 and 20% by weight, preferablybetween 3 and 15% by weight, of the solids content of the composition,the improvement in the mechanical properties observed on the compositesgenerally increasing with this content. Below 1% by weight of protectionagent(s) according to the invention, the improvement in the mechanicalproperties is insignificant, while above 20% by weight of protectionagent(s) according to the invention the cost of the size becomes veryhigh without any further improvement in the properties.

Apart from this or these protection agents, the sizing compositionaccording to the invention may comprise one or more other silanes actingas coupling agents, especially one or more silanes commonly used insizes, such as an amino silane, a vinyl silane,γ-methacryloxypropyltrimethoxysilane, etc. The content of this or theseother silanes is generally less than 10% by weight of the solids contentof the composition according to the invention, the maximum content ofsilane(s), all silanes included, not exceeding 30% by weight of thesolids content of the composition according to the invention.Preferably, when the yarns according to the invention are intended forreinforcing at least one vinyl ester material (or possibly a polyesteror epoxy material), the composition comprises, in addition to theabovementioned protection agent(s), at least oneγ-methacryloxypropyltrimethoxysilane or possibly a vinyl silane. Thesizing composition may also comprise other coupling agents such astitanates, zirconates, etc. or organic compounds promoting the couplingbetween the glass yarns and certain organic materials.

The protection agent or agents may be added directly to an existingsizing composition, for example to any sizing composition normally usedin the intended application, or the sizing composition according to theinvention may be obtained by mixing all the required components in oneor more steps. In general, the silane according to the invention isadded to the composition in hydrolyzed form. Other components, such asthose normally used in this type of composition, may also be present inthe sizing composition according to the invention.

In particular, the composition according to the invention generallycomprises, in addition to the silane(s), at least one bonding (orfilm-forming) agent, this agent having an effect on the processabilityof the yarn, for example ensuring the linking-together (integrity) ofthe filaments within the yarns and thus making them easier to be handledand/or allowing better impregnation of the yarns by the matrices to bereinforced. This agent, well known in the sizing field, is usuallypresent in the form of a compound having one or more epoxy functionalgroups, for example an epoxy of bisphenol A or F, a novolac epoxy, etc.and/or in the form of a compound having one or more polyester functionalgroups, such as an unsaturated polyester, and/or an epoxy ester, etc. Ingeneral, the sizing composition according to the invention comprises atleast two bonding agents, one in particular allowing good sheathing ofthe yarns and the other ensuring good impregnation by the matrix to bereinforced. The content of bonding agent(s) is generally less than 90%by weight of the solids content of the composition and is preferablybetween 50 and 85% by weight of the solids content of the composition.

Likewise, the composition generally comprises at least one lubricatingagent, this agent protecting the yarns from abrasion during and afterthe fiberizing. This agent, well known in the sizing field, is usuallyin the form of a mixture of alkyls, alkyl benzenes, fatty esters, fattyalcohols, surfactants, etc. In general, the sizing composition accordingto the invention comprises at least two lubricating agents, such as amineral oil and a fatty acid ester for example, one of them allowinglubrication of the yarns in a wet medium at the moment of fiberizing andthe other allowing subsequent lubrication in a dry medium. The contentof lubricating agent(s) is generally less than 20% by weight of thesolids content of the composition and is preferably between 5 and 15% byweight of the solids content of the composition.

The composition according to the invention may also comprise otheractive components, especially components commonly used in sizingcompositions, such as textile (or softening) agents, antistatic agents,emulsifiers or surfactants, wetting agents, etc., the proportion ofthese other agents generally ranging from 0 to 15% by weight of thesolids content of the composition.

Apart from the aforementioned active components, the composition mayalso comprise at least one solvent, especially water, as mentionedabove. Certain active components may be already in solution or dispersedin a solvent while they are being added to the mixture that has to givethe sizing composition according to the invention and/or the solvent orsolvents may be added to the mixture with or after the active componentsso as to obtain the viscosity and the proportions that are usuallyrequired for depositing the composition on the filaments.

The composition is generally deposited in one step on the filamentsbefore they are assembled into yarns, as explained above. However, thecomponents of the composition coating the yarns may be deposited inseveral steps; for example, the silane defined according to theinvention may be deposited, in hydrolyzed form, independently of theother constituents of the composition, preferably before these otherconstituents are deposited, so that the silane is brought into directcontact with the constituent glass of the yarn.

The loss on ignition of the yarns according to the invention isgenerally between 0.3 and 2% by weight of the yarns and preferablybetween 0.5 and 1.5% by weight of the yarns.

The composites obtained from the yarns according to the inventioncomprise at least one organic material and/or at least one inorganicmaterial, and reinforcement yarns, at least some of the reinforcementyarns being the yarns according to the invention. The reinforcementyarns according to the invention are preferably combined withthermosetting material (vinyl esters, polyesters, phenolics, epoxides,acrylics, etc.), advantageously with vinyl esters, these being morecorrosion-resistant than other organic materials, and/or with cementousmaterial (cement, concrete, mortar, gypsum, compounds formed by reactionbetween lime, silica and water, etc.), it being possible for thereinforcement of the cementous materials to be carried out directly orindirectly (after being combined with an organic material). Particularlyuseful composites according to the invention are the composites formedfrom at least one plastic (advantageously organic) material and fromreinforcement yarns according to the invention.

The following nonlimiting examples illustrate the glass yarns and thecompositions according to the invention and make it possible to comparethe mechanical properties obtained, before and after aging, oncomposites produced from glass yarns according to the invention with themechanical properties obtained on composites produced from conventionalglass yarns.

EXAMPLE 1

In this example, glass filaments 17 μm in diameter were obtained bydrawing strands of molten glass, this glass being an AR glass having thefollowing composition expressed in percentages by weight: SiO₂ 61.6%Al₂O₃  0.9% ZrO₂ 16.8% CaO  5.4% Na₂O 14.7% K₂O  0.3% Fe₂O₃ 0.05%Fluorine 0.26% SO₃ 0.05% TiO₂   0.1%.

These filaments were coated, during their passage before they areassembled into yarns, with the following sizing composition expressed inpercentages by weight: 1 100 molecular mass epoxy ester⁽¹⁾  1.2%biphenol A epoxy⁽²⁾  3.6% γ-methacryloxypropyltrimethoxysilane  0.35%coupling agent⁽³⁾ mineral oil⁽⁴⁾  0.32% fatty acid ester⁽⁵⁾  0.54%aminodimethylbutyltrimethoxysilane⁽⁶⁾  0.35% (silane/protection agentaccording to the invention) water 93.64%⁽¹⁾Sold, diluted to 40%, under the reference NEOXIL 962 D by DSM;⁽²⁾Sold, diluted to 60%, under the reference EPIREZ 3510W60 byResolution;⁽³⁾Sold under the reference SILQUEST A 174 by Osi Specialities;⁽⁴⁾Sold under the reference TORFIL LA4 by Lamberti;⁽⁵⁾Sold under the reference SYNTOFIL by Lamberti;⁽⁶⁾Sold under the reference Y11637 by Osi Specialities.

The filaments were combined into yarns, which were wound in the form ofrovings, and then the rovings were heated at 130° C. for 12 hours, so asin particular to dry them. The yarns obtained had a linear density of545 tex and a loss on ignition of 1.1%.

The yarns were then extracted from the windings in order to measuretheir tensile breaking tenacity under the conditions defined by the ISO3341 standard. The tensile breaking tenacity measured on 8 to 10 testsamples was about 36 g/tex (standard deviation of 2 g/tex).

The abrasion resistance of the yarns was also determined by weighing theamount of fuzz formed after passing the yarns over a series of rods. Forthe various yarns coated with the cured size described in the presentexample, the amount of fuzz after the test was around 28 mg per kg ofyarns tested.

Composite plaques with parallel yarns were also produced in accordancewith the NF T 57-152 standard from the yarns obtained. The reinforcedresin was a vinyl ester resin sold under the reference DERAKANE 411/45by Dow Chemical, to which were added, per 100 parts by weight of vinylester resin, 1.5 parts of a hardener sold under the reference TRIGONOX239 by Akzo, 0.08 parts of a cure accelerator sold under the referenceNL 51P by Akzo, 0.2 parts of a cure accelerator sold under the referenceNL-63-100 by Akzo and 0.1 parts of an inhibiter sold under the referencePROMOTER C by Akzo.

The plaques produced were then heat treated and the mechanicalproperties exhibited by these plaques, in flexure and in shear, weremeasured, according to the ISO 14125 and ISO 14130 standardsrespectively, on the test specimens left beforehand for 72 h at 21° C.(with 50% ambient relative humidity). The tensile flexural strength, fora glass content brought back (normalized) to 100%, was about 2 320 MPa(standard deviation 80 MPa) in the case of ten test specimens and theshear strength was about 70 MPa (standard deviation 0.4 MPa).

The mechanical properties of the test specimens were also measured afteraging, consisting in putting the test specimens in a glass of boilingwater for 72 h and then testing them five hours later. The flexuralstrength after aging, for a glass content brought back to 100%, wasabout 1 800 MPa (standard deviation 120 MPa) and the shear strength wasabout 52 MPa (standard deviation 1.3 MPa).

COMPARATIVE EXAMPLE 1

This example was produced as in Example 1 but with the silane accordingto the invention replaced, in the sizing composition, by(N-benzylaminoethyl)aminopropyl-trimethoxysilane sold under thereference A1128 by Osi Specialities.

The yarns obtained had a linear density of 623 tex and a loss onignition of 1%.

The tensile breaking tenacity was about 38 g/tex (standard deviation 3g/tex).

The amount of fuzz after the abrasion resistance test on the yarns wasaround 19 mg per kg of yarn tested.

Before aging, the flexural strength, for a glass content brought back to100%, was about 2350 MPa (standard deviation 80 MPa) and the shearstrength was about 52 MPa (standard deviation 2.2 MPa) and, after aging,the flexural strength, for a glass content brought back to 100%, wasabout 1007 MPa (standard deviation 34 MPa) and the shear strength wasabout 20 MPa (standard deviation 0.3 MPa).

COMPARATIVE EXAMPLE 2

This example was produced as in Example 1 but with the silane accordingto the invention replaced, in the sizing composition, byaminoethylaminopropyl-trimethoxysilane sold under the reference Z6020 byDow Corning.

The yarns obtained had a linear density of 654 tex and a loss onignition of 0.9%.

The tensile breaking tenacity was about 35 g/tex (standard deviation 3g/tex).

The amount of fuzz after the abrasion resistance test on the yarns wasaround 34 mg per kg of yarn tested.

Before aging, the flexural strength, for a glass content brought back to100%, was about 2380 MPa (standard deviation 50 MPa) and the shearstrength was about 54 MPa (standard deviation 1.3 MPa) and, after aging,the flexural strength, for a glass content normalized to 100%, was about1130 MPa (standard deviation 41 MPa) and the shear strength was about 23MPa (standard deviation 0.7 MPa).

It may be seen that the yarns according to the invention make itpossible to obtain composites having mechanical properties after agingin a wet medium that are substantially improved over those of thecomposites obtained from conventional yarns presented as comparativeexamples, the presence of the protection agent furthermore not impairingthe other properties of the yarns, for example the windability or theweavability of the yarns. It should be noted that the results afteraging in an acid medium or after aging in a basic medium (these resultsare not reported, differing little between the present examples) arealso very satisfactory.

The yarns according to the invention may be used to produce variouscomposites and especially pipes, hoses and tanks by winding or toproduce pultruded rods that can be used to replace concrete rebars, etc.

1. A reinforcement yarn coated with a sizing composition comprising atleast one silane satisfying the following formula:Si(R¹)(R²)(R³)(R⁴) wherein: R¹ and R² are selected from at least onegroup consisting of:—H, —Cl, —O—R⁵, —O—R⁶—O—R⁵, —O—(C═O)—R⁵, and —O—R⁶—(C═O)—R⁵; R³ isselected from at least one group consisting of:—Cl, —O—R⁵, —O—R⁶—O—R⁵, —O—(C═O)—R⁵, and —O—R⁶—(C═O)—R⁵; R⁵ and R⁶ areselected from hydrocarbon radicals having from 1 to 4 carbon atoms inthe main chain; R⁴═—R⁷—NHR⁸; R⁷ is selected from branched hydrocarbonradicals having from 2 to 6 carbon atoms in the main chain; R⁸ beingchosen is selected from at least one group consisting of:—H, —R⁹—NH₂, and —R¹⁰—NH—R⁹—NH₂; R⁹ is selected from hydrocarbonradicals comprising from 1 to 12 carbon atoms or from carbonyls; and R¹⁰being chosen is selected from hydrocarbon radicals having from 1 to 6carbon atoms in the main chain.
 2. The reinforcement yarn as claimed inclaim 1, wherein R¹═R²═R³═—CH₃O, and R⁴═—CH₂—CH₂—C(CH₃)₂—CH₂NH₂ or—CH₂—C(CH₃)₂—CH₂—NH₂.
 3. The reinforcement yarn as claimed in claim 1,wherein the composition further comprises at least oneγ-methacryloxy-propyltrimethoxysilane or at least one vinyl silane. 4.The reinforcement yarn as claimed in claim 1, wherein the compositionfurther comprises at least one bonding agents.
 5. The reinforcement yarnas claimed in claim 1, wherein the composition further comprises atleast one lubricating agents.
 6. The reinforcement yarn as claimed inclaim 1, wherein said yarn is obtained from an alkali-resistant glass.7. The reinforcement yarn as claimed in claim 1, wherein said yarn iscapable of reinforcing plastic materials.
 8. A sizing composition forreinforcement yarns comprising at least one silane satisfying thefollowing formula:Si(R¹)(R²)(R³)(R⁴) wherein R¹ and R² are chosen selected from at leastone group consisting of:—H, —Cl, —O—R⁵, —O—R⁶—O—R⁵, —O—(C═O)—R⁵, and —O—R⁶—(C═O)—R⁵; R³ isselected from at least one group consisting of:—Cl, —O—R⁵, —O—R⁶—O—R⁵, —O—(C═O)—R⁵, and —O—R⁶—(C═O)—R⁵; R⁵ and R⁶ areselected from hydrocarbon radicals having from 1 to 4 carbon atoms inthe main chain;R⁴═—R⁷—NHR⁸; R⁷ is selected from branched hydrocarbon radicals havingfrom 2 to 6 carbon atoms in the main chain; R⁸ is selected from at leastone group, consisting of:—H, —R⁹—NH₂, and —R¹⁰—NH—R⁹—NH₂; R⁹ is selected from hydrocarbonradicals comprising from 1 to 12 carbon atoms or from carbonyls; and R¹⁰is selected from hydrocarbon radicals having from 1 to 6 carbon atoms inthe main chain.
 9. A composite comprising at least one organic materialand/or one inorganic material and the reinforcement yarn as claimed inclaim 1.